1. Field of the Invention
The invention relates to an electronic assembly for integrated mechatronic systems with a housing cover, at least one electrical connection in the form of a printed circuit board, and a housing base; the invention also relates to a method for producing such an electronic assembly, in particular for transmission or engine controllers in the automotive industry.
Electronic assemblies for integrated mechatronic systems and in particular control devices generally have a plurality of electronic components, which are connected to other components outside the control device. They are normally inserted into special housings to protect them from environmental influences or mechanical stresses. The housings also fulfill an important shielding function. These functions become more important, the more components are used directly in situ as integrated mechatronic systems, in other words in particular electronic control systems, in a transmission or engine for example. They are subject to a plurality of environment-related requirements. As well as long-term stability and fail-safety of the controller, higher operating temperatures, chemical stresses due to engine or transmission oil and the mechanically stressful environment of the engine or transmission due to the constant vibration load also play a major role. It is therefore essential for the sensitive electronic systems to be protected from such influences as far as possible.
A correspondingly sealed connection with long-term stability between the housing cover and the housing base is required to allow reliable sealing from the environment outside the housing.
2. Prior Art
DE 10 2004 033 559 A1 describes a three-part structure of a housing for an electronic assembly, having a housing cover, at least one housing wall and a housing base to cover the substrate of the electronic system. A seal between the housing cover and the housing wall and/or the base is enabled in that a special sealing mass is introduced. The sealing mass according to the cited publication can also establish the adhesion between the housing wall and housing base and/or cover as a further function.
The disadvantage of this arrangement is that fatigue phenomena can occur in the sealing material during the course of the useful life of such a control device, in particular in a highly aggressive environment as with transmission control devices, which are surrounded by chemically extremely active transmission oil and at the same time have to withstand high temperatures. Therefore provision is generally made for rivets or screws to fix the cover in a sealed manner.
DE 33 15 655 A1 describes an electrical connection using flexible conductor tracks. The flexible conductor tracks are inserted at a connecting point between the housing base and the cover and are also sealed off by way of molded seals on the housing base and the cover. These flexible conductor tracks can be passed from the connecting point directly to the electrical assembly in the interior of the housing. This allows a relatively flexible arrangement of the components.
An arrangement for the sealed passage of a flexible printed circuit board through a housing wall joint is also known from DE 199 14 469 C1, with which two molded seals with a sealing profile are disposed in the joint region, producing a longitudinal displacement of the flexible printed circuit board when the two parts of the housing wall are joined.
This however also has the disadvantage that sealing by means of molded seals cannot withstand the high levels of stress imposed mechanically/by vibration and in respect of chemical stability over the entire useful life of the control device specifically in an aggressive environment and therefore the housing cover is also fixed using measures such as rivets or screws.